Re: Refinishing chrome
If you still have the metal fixture, you can send it to be re-plated, and it'll come back looking shiny new.
If you're missing the fixture, you pretty much have to browse ebay or boat junkyards looking for it, or if possible you can even have a copy of one you do have made by a casting shop.
There are also aftermarket copies of fixtures made by certain vintage boat shops if it's a more common item and manufacturer.
Erik